<!DOCTYPE html>
<!--08.尚硅谷_css2.1_等高布局-->
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<!--
			1.两边固定  当中自适应
			2.当中列要完整显示
			3.当中列要优先加载
		-->
		
		<!--
			浮动:	搭建完整的布局框架
			margin 为负值:调整旁边两列的位置(使三列布局到一行上)
			使用相对定位:调整旁边两列的位置（使两列位置调整到两头）
		-->
		
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			body{
				min-width: 600px;
			}
			#content{
				overflow: hidden;
				padding: 0 200px;
			}
			#header,#footer{
				height: 20px;
				text-align: center;
				border: 1px solid  deeppink;
				background: gray;
			}
			#content .middl,#content .left,#content .right{
				padding-bottom: 10000px;
				margin-bottom: -10000px;
			}
			#content .middle{
				float: left;
				width: 100%;
				background: pink;
				/*padding: 0 200px;*/
			}
			#content .left{
				position: relative;
				left: -200px;
				margin-left: -100%;
				float: left;
				width: 200px;
				background: yellow;
			}
			#content .right{
				position: relative;
				right: -200px;
				margin-left: -200px;
				float: left;
				width: 200px;
				background: yellow;
			}
			
			
			
			.clearfix{
				*zoom: 1;
			}
			.clearfix:after{
				content: "";
				display: block;
				clear: both;
			}
		</style>
	</head>
	<body>
		<div id="header">header</div>
		<div id="content" class="clearfix">
			<div class="middle">
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
				<h4>middle</h4>
			</div>
			<div class="left">left</div>
			<div class="right">right</div>
		</div>
		<div id="footer">footer</div>
	</body>
</html>
